Video recording and reproducing apparatus for recording a video signal and an indexing signal

ABSTRACT

A recording and reproducing apparatus is disclosed in which video signal and indexing signal are separately recorded in video signal areas and subcode areas, respectively, of diagonal tracks formed on a tape by a rotating head. The apparatus has a tape driver for driving the tape, add/erase command keys for generating add/erase command to add/erase the indexing signal, an indexing signal control for setting and resetting the indexing signal, and a recording device for recording the video signal to the video signal area and, if any, the indexing signal to the subcode area of each track. An editing control is provided for controlling the indexing signal control in response to the add/erase command such that the indexing signal is first recorded as a reset state for a first predetermined amount and then recorded as a set state.

This application is a continuation, of application Ser. No. 08/260,998,filed Jun. 16, 1994, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a recording and reproducing apparatusfor recording a video signal together with indexing information to tape,and for reproducing the recorded information by means of rotating heads,and particularly to a recording and reproducing apparatus for recordingeditable indexing information.

2. Description of the Prior Art

Video cassette recorders (VCR) and other recording and reproducingapparatuses using a tape medium are now widely and commonly available.Further reductions in device size enabled by high density recordingtechniques and digital technologies are also being developed. In digitalmedia such as these, a subcode is usually also recorded when recordingthe data signal. This subcode is an integral part of the complete datasignal, and may be or include an indexing ID showing the recording startposition of the data, an absolute time code showing the absoluteposition of the data on tape, or a user-defined time code. Examples ofdevices recording such a subcode include DAT (Digital Audio Taperecorders) and 8 mm VCRs. It is commonly known that the DAT and 8 mm VCRstandards specify an editable subcode that can be separately re-recordedwhile preserving the recorded video signal and audio signal.

The following problems, however, have existed with this conventionalsubcode, particularly when rewriting the indexing information.

For example, let us assume that a 9-sec. indexing ID is recorded to acertain position on tape. The fixed (predetermined) recording time ofthe indexing ID is determined with respect to the signal detectioncapacity during high speed searches, and it follows that the detectioncapacity increases relative to the length of the indexing ID recordingtime. This characteristic is particularly strong when the indexing ID isrecorded to part of a diagonal track. If new indexing information isthen recorded starting from some position in the fixed length recordingtime of this indexing ID (for example, at the position 4 sec. from thestart of the indexing ID recording period), the existing indexing ID isedited and this new indexing ID is recorded for 9 sec. from thatposition. As a result of recording this new indexing ID for 9 sec., acontinuous indexing ID recording period 13 sec. in duration iseffectively recorded to the tape by means of this prior art method. Theproblem with this method is that it becomes no longer possible toaccurately determine the recording start position of the new indexingID.

It is also possible that when recording a new indexing ID for this9-sec. period, this fixed length period may overlap the startingposition of a previously recorded indexing ID. For example, a previouslyrecorded indexing ID may have been recorded for the standard 9 sec.period starting from a position 4 sec. from the start of a newlyrecorded indexing ID. Recording this new indexing ID for 9 sec. willlikewise result in a continuous indexing ID recording period 13 sec. induration being recorded to the tape. A similar problem again results: itis not possible to accurately determine the recording start position ofthe previously recorded indexing ID.

The above two problems become extremely inconvenient when the recordingstart position of the indexing ID is particularly meaningful (e.g., whenthe indexing ID identifies a scene or selection change). The startingposition of editing operations intended to start from this indexing IDwill therefore be offset, and the ID will be effectively rendereduseless for precision editing tasks.

SUMMARY OF THE INVENTION

Therefore, the object of the present invention is to provide a recordingand reproducing apparatus which provides a subcode area to whichindexing information is recorded so that both the recording startposition of previously recorded indexing information and the recordingstart position of newly recorded indexing information can be determinedafter rewriting the indexing information, regardless of where indexinginformation was previously recorded.

To achieve this object, according to the present invention, a recordingand reproducing apparatus for recording video signal and indexing signalto separate video signal areas and subcode areas, respectively, ofdiagonal tracks formed on a tape by a rotating head, comprises: tapedrive means for driving the tape; add command generator for generatingan add command to add said indexing signal; indexing signal control forsetting and resetting said indexing signal; recording means forrecording the video signal to the video signal area and the indexingsignal, if any, to the subcode area of each track; and editing controlmeans for controlling said indexing signal control in response to saidadd command such that said indexing signal is first recorded as a resetstate for a first predetermined amount and then recorded as a set state.

Also, according to the present invention, a recording and reproducingapparatus for recording video signal and indexing signal to separatevideo signal areas and subcode areas, respectively, of diagonal tracksformed on a tape by a rotating head, comprises: tape drive means fordriving the tape; add command generator for generating an add command toadd said indexing signal; indexing signal control for setting andresetting said indexing signal; recording means for recording the videosignal to the video signal area and the indexing signal, if any, to thesubcode area of each track; reproducing means for reproducing a recordedsignal from said tape; switching means for switching between a recordingmode in which said recording means is connected to said head and areproducing mode in which said reproducing means is connected to saidhead; indexing signal detection means for detecting set and reset statesof said indexing signal during said reproducing mode; and editingcontrol means for controlling said indexing signal control in responseto said add command such that the tape is reproduced for a secondpredetermined amount to detect any leading edge of previously recordedindexing signal, and if a leading edge of previously recorded indexingsignal is detected, said indexing signal is recorded as a set state froma first position where said add command is generated to a secondposition which is behind said leading edge by said first predeterminedamount.

Also, according to the present invention, a recording and reproducingapparatus for recording video signal and indexing signal to separatevideo signal areas and subcode areas, respectively, of diagonal tracksformed on a tape by a rotating head, comprises: tape drive means fordriving the tape; erase command generator for generating an erasecommand to erase a previously stored indexing signal; indexing signalcontrol for setting and resetting said indexing signal; recording meansfor recording the video signal to the video signal area and the indexingsignal, if any, to the subcode area of each track; reproducing means forreproducing a recorded signal from said tape; switching means forswitching between a recording mode in which said recording means isconnected to said head and a reproducing mode in which said reproducingmeans is connected to said head; indexing signal detection means fordetecting the indexing signal during said reproducing mode; and editingcontrol means for controlling said indexing signal control in responseto said erase command such that the tape is rewound to a third positionpast a third predetermined amount from a leading edge of said previouslystored indexing signal, then the tape is reproduced to detect a fourthposition corresponding to a trailing edge of said previously storedindexing signal, then indexing signal is recorded as a reset state fromsaid third position to said fourth position to erase said previouslystored indexing signal.

Also, according to the present invention, a recording and reproducingapparatus for recording video signal and indexing signal to separatevideo signal areas and subcode areas, respectively, of diagonal tracksformed on a tape by a rotating head, said apparatus comprising; tapedrive means for driving the tape; erase command generator for generatingan erase command to erase a previously stored indexing signal; indexingsignal control for setting and resetting said indexing signal; recordingmeans for recording the video signal to the video signal area and theindexing signal, if any, to the subcode area of each track; reproducingmeans for reproducing a recorded signal from said tape; switching meansfor switching between a recording mode in which said recording means isconnected to said head and a reproducing mode in which said reproducingmeans is connected to said head; indexing signal detection means fordetecting the indexing signal during said reproducing mode; and editingcontrol means for controlling said indexing signal control in responseto said erase command such that when the previously stored indexingsignal to be erased is preceded by another previously stored indexingsignal with an interspace between said two previously stored indexingsignal being less than a fourth predetermined amount, said interspace isrecorded with set state of said indexing signal to absorb saidpreviously stored indexing signal to said another previously storedindexing signal.

When a recording, and reproducing apparatus according to the presentinvention thus comprised overwrites new information to a previouslyrecorded tape from some midposition in a previously recorded indexinginformation period of a fixed duration, or when the recording startposition of a previously recorded indexing information period of fixedduration is within the fixed duration period to which new indexinginformation is to be recorded, it is possible to determine the recordingstart positions both before and after re-writing. As a result, using arecording and reproducing apparatus of the invention, a VCR or otherrecording and reproducing apparatus with an excellent indexinginformation edit function can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given below and the accompanying diagrams wherein:

FIG. 1 is a block diagram showing a recording and reproducing apparatusaccording to the present invention, particularly showing the partsnecessary for recording,

FIG. 2 is a diagram showing the placement of is rotating heads on thecylinder in the preferred embodiment of the invention,

FIGS. 3A and 3B are block diagrams showing the structure of the subcodearea in the preferred embodiment of the invention,

FIG. 4 is a table showing the content and positions of the ID and dataparts of the subcode in the preferred embodiment of the invention,

FIG. 5 is a table showing a detail of the content and positions of thesubcode recorded to the data part of the subcode in the preferredembodiment of the invention,

FIG. 6 is a block diagram of a recording and reproducing apparatusaccording to the present invention, particularly showing the partsnecessary for re-writing the indexing ID, SRID,

FIGS. 7A and 7B taken together as shown in FIG. 7 show a flow chart forrecording the indexing ID, SRID,

FIG. 8 is a detailed block diagram of an editing timing generator shownin FIG. 6,

FIGS. 9A, 9B, 9C and 9D are timing charts showing the subcode editingtiming in the preferred embodiment of the invention,

FIGS. 10A and 10B are charts showing the tape movement for recording theindexing ID in two different cases,

FIG. 11 is a table showing the content and positions of the ID and dataparts of the subcode in the preferred embodiment of the invention,

FIGS. 12A and 12B taken together as shown in FIG. 12 show a flow chartfor erasing the indexing ID, SRID, and

FIGS. 13A and 13B are charts showing the tape movement for erasing theindexing ID in two different cases.

DESCRIPTION OF PREFERRED EMBODIMENTS

The preferred embodiment of a recording and reproducing apparatusaccording to the present invention is described below with reference tothe accompanying figures. FIG. 1 is a block diagram illustrating therecording and reproducing apparatus particularly showing the partsnecessary for recording data on a tape.

Referring to FIG. 1, the tracks 24-0 to 24-9 are formed on a magnetictape 1 by rotating heads 2a and 2b mounted on a cylinder (not shown inthe figure).

The tape driver 7 comprises a capstan motor 4, a pinch roller 5, and acapstan control circuit 6. A subcode generator 21 comprises an ID data 1generator 13, an ID data 2 generator 14, a subdata 1 generator 15, asubdata 2 generator 16, a synchronization signal generator 17, and asynthesizer 20. The recording and reproducing apparatus furthercomprises a video signal generator 8, a clock generator 9, a segmentingcircuit 10, a frame synchronization signal generator 11, a trackingsignal generator 12, a recorder 22, and a rotary head controller 23.

Note that in the present embodiment, two rotating heads 2a and 2b areused for recording or reproducing two tracks simultaneously. Thelocations of the rotating heads on the cylinder 3 in this embodiment areshown in FIG. 2.

A positioning signal area 27 is provided in part of the tracking signalarea 28 formed at the beginning of each track on the magnetic tape 1 asshown in FIG. 1. A positioning signal is recorded to this positioningsignal area 27. The frequency of this positioning signal is a relativelyhigh frequency so that the positioning signal may have less influence ofthe crosstalk from adjacent tracks and other signal interference. Apilot signal for tracking is recorded to the tracking signal area 28.This pilot signal is one of two frequencies f1 or f2 recorded toalternating tracks. The frequency of these two pilot signals is arelatively low frequency that is resistant to azimuth loss of therotating heads 2a and 2b. The video signal is recorded to the videosignal area 25, and the subcode is recorded to the subcode area 26 ofeach track.

The recording operation of the apparatus shown in FIG. 1 is describednext. During recording, the magnetic tape 1 is transported by the pinchroller 5 and the capstan motor 4, the rotational velocity of which iscontrolled by the capstan control circuit 6.

The video signal generator 8 produces a signal of approximately 30frames per second (fps), in which one frame constitutes one televisionscreen. The segmenting circuit 10 then divides each frame signal intoten segments so that ultimately the video signal for one frame isrecorded to ten tracks, such as to tracks 24-0 through 24-9. Thesegmented video signal is input to the recorder 22 together with asegment number.

The clock generator 9 generates a clock synchronized to the input videosignal. In this case, the video signal is input at 30 fps, and a 150-Hzclock synchronized to the video signal is generated.

The tracking signal generator 12 generates the tracking signal. Thetracking signal contains the positioning signal, and the two pilotsignals of frequencies f1 and f2 differing according to the clock outputby the clock generator 9. This tracking signal is input to the recorder22.

The frame synchronization signal generator 11 generates a 30-Hz framesynchronization signal synchronized to the frame of the input videosignal.

The ID data 1 generator 13 generates ID data 1, which includes the blockidentification code, indexing ID (hereafter "SRID"), and the programnumber. ID data 1 is then input to the synthesizer 20.

The indexing ID (SRID) is a code written on, or erased from, the tapeaccording to the user's operation, and is used for quick accessing tothe position where the SRID is inserted during the fast forward orrewinding operation. As will be apparent from the further description,the present invention provides new system for recording/erasing the SRIDwithout any error.

The ID data 2 generator 14 generates ID data 2, which includes the blockidentification code, application ID (hereafter "APID"), and the controlID (hereafter "COID"). ID data 2 is also input to the synthesizer 20.

The subdata 1 generator 15 generates subdata 1 containing the absoluteposition information (e.g., tape counter or absolute time code). Subdata1 is also input to the synthesizer 20.

The subdata 2 generator 16 generates subdata 2 containing userinformation (e.g., recording date and time). Subdata 2 is also input tothe synthesizer 20.

The synchronization signal generator 17 generates the synchronizationsignal. The subcode recorded to the subcode area of each track isrecorded to plural (e.g., 12) subareas. These subareas are hereafterreferred to as "synchronization blocks" (SB). The synchronization signalis the signal identifying the recording start position of thesynchronization block. The synchronization signal is also input to thesynthesizer 20.

The synthesizer 20 first recognizes the segment numbers (0-9) in oneframe of the segmented video signal input to the recorder 22 based onthe clock output from the clock generator 9 and the framesynchronization signal output from the frame synchronization signalgenerator 11. The combination of ID data and subdata input to therecorder 22 is then switched according to the segment number. Morespecifically, when the segment number is 0, 1, or 2, a subcode mixingthe synchronization signal, ID data 1, and subdata 1 is input; when thesegment number is 3 or 4, a subcode mixing the synchronization signal,ID data 2, and subdata 1 is input; when the segment number is 5 or 6, asubcode mixing the synchronization signal, ID data 2, and subdata 2 isinput; and when the segment number is 7, 8 or 9, a subcode mixing thesynchronization signal, ID data 1, and subdata 2 is input.

Thus, ID data 1 is input to the recorder 22 when the segment number is0, 1, 2, 7, 8, or 9, but the same data content is input throughout asingle frame regardless of the segment number.

ID data 2 is similarly input to the recorder 22 when the segment numberis 3, 4, 5 or 6, and the same data content is also input throughout asingle frame regardless of the segment number.

Subdata 1 is similarly input to the recorder 22 when the segment numberis 0, 1, 2, 3, or 4, and as with ID data 1, the same data content isinput throughout a single frame regardless of the segment number.

Subdata 2 is input to the recorder 22 when the segment number is 5, 6,7, 8, or 9, and the same data content is also input throughout a singleframe regardless of the segment number.

As a result, ID data 1, ID data 2, subdata 1, and subdata 2 are eachcontained in the subcode in four or more consecutive segment numbers.

Based on the clock output of the clock generator 9, the recorder 22 thenoutputs a recording signal whereby the segmented video signal, subcode,and tracking signal are recorded by the rotating heads 2a and 2b torespective areas.

The rotary head controller 23 controls the velocity of the cylinder 3 onwhich the rotating heads 2a and 2b are mounted synchronized to the clockoutput of the clock generator 9.

As a result of this operation, tracks as shown in FIG. 1 are formed onthe magnetic tape 1. The detailed structure of the subcode area 26 inone track is shown in FIG. 3A, and the detailed structure of onesynchronization block of the subcode is shown in FIG. 3B.

As shown in FIG. 3A, the subcode area in one track comprises twelvesynchronization blocks (SB0-SB11), and each synchronization blockcomprises a synchronization part 100, ID part 110, and data part 120 asshown in FIG. 3B.

A two byte signal identifying the recording start position of thesynchronization block is recorded to the synchronization part 100. TheID part 110 includes two bytes (ID0 and ID1, one byte each) in ID data111, and one byte in IDP 112, for a total of three bytes in the ID part110. The ID data 111 is described in detail later with reference to FIG.4. A parity signal is recorded as IDP 112. The IDP 112 parity signal isused to detect (and thus correct) signal reading errors from thesynchronization part 100 to the ID part 110 in the synchronizationblock. By recording the IDP 112 to this position in one synchronizationblock, the ID data 111 recorded as ID0 and ID1 can be read by readingfrom synchronization part 100 to ID part 110. It is not necessary atthis time to read the complete, synchronization block (from thesynchronization part 100 to the data part 120). This is particularlyeffective for data reproduction when the scan path of the rotating headscrosses the tape tracks diagonally during, for example, a high speedsearch.

The data part 120 comprises a five byte subdata block 121 and a two bytedata parity block 122. The subdata 121 is described in detail later withreference to FIG. 4. The data parity block 122 is a parity signal. Thisdata parity block 122 is similarly used to detect (and thus correct)signal reading errors from the synchronization part 100 to the data part120 in the synchronization block. The subdata in the data part 120 canbe read when the signal from the synchronization part 100 to the dataparity block 122 can be read.

FIG. 4 shows the content and locations of the ID data 111 and thesubdata 121 of the subcode. Note that the track numbers (0-9) shown inFIG. 4 coincide with the segment numbers referenced above. Thus, ID data1 and ID data 2 are switched as the content of the ID data 111, andsubdata 1 and subdata 2 are switched as the content of the subdata 121according to the track number.

ID data 1 is thus recorded as the ID data to track numbers 0, 1, 2, 7,8, and 9. Although it is recorded in sections to a single frame, ID data1 is recorded to the ID part of the subcode area to six consecutivetracks if tracks from adjacent frames are also considered. This ID partof adjacent tracks to which the same ID data is recorded is hereafterreferred to as the "ID block," and the data part of adjacent tracks towhich the same subdata is recorded is hereafter the "subdata block."

The ID part 110 of ID block 1 to which ID data 1 is recorded isdescribed below in the head scanning order, i.e., the order the data isrecorded to tape. As mentioned above, the ID data 111 comprises twobytes, ID0 and ID1. A total nine bits is recorded to ID0 in thefollowing sequence: a 4-bit synchronization block number 113, a 2-bitblock identification code 114, a 1-bit SRID 115, and the first bit ofthe nine bit program number 116 (PN2-PN0). The remaining eight bits ofthe program number 116 are recorded to ID1 in ID data 1.

The synchronization block number 113 identifies which synchronizationblock 0-11 in the subcode area 26 is recorded to the one track. Theblock ID code 114 distinguishes the four possible block combinationsthat can be made in one frame from ID data 1 and 2 and subdata 1 and 2as shown in FIG. 4. The same ID and program number are recorded as theSRID 115 and program number 116 (PN2-PN0), respectively, in one frame.

The block ID code 114 of track numbers 0, 1, and 2 is b"00" in which theprefix b indicates the binary expression, and the block ID code 114 oftrack numbers 7, 8, and 9 is b"11". The synchronization block number 113ranges from 0-11.

ID data 2 is recorded as the ID data 111 of the ID part 110 in tracknumbers 3, 4, 5, and 6 (ID block 2). Described below in the headscanning order, a 4-bit synchronization block number 113 and 2-bit blockID code 114, each with the same meaning as in ID data 1, are recordedfirst. The next two bits 117 are b"00". A 2-bit APID 118 and 6-bit COID119 are then recorded. The APID 118 is identification informationindicating the type of data recorded to the ID part 110 and the datapart 120. Recording the APID signal makes it possible to change the datacontent recorded to the data part and the ID part. The COID may alsocontain ID information for skip-search operations, or table of contents(TOC) ID data.

The TOC can be read to create a menu of the video signal contentrecorded to the tape, and the TOC ID indicates whether a TOC is recordedto that period. Note that the TOC is normally recorded together with thevideo signal to the video signal recording area. Note, also, that theAPID 118 and COID 119 ID data remain constant throughout one frame. Theblock ID code 114 b"01" is recorded to track numbers 3 and 4, and b"10"is recorded to track numbers 5 and 6. The synchronization block number113 ranges from 0-11.

The subdata 121 recorded to the data part 120 is described next. Theabsolute position information (subdata 1) is recorded as the subdata(subdata block 1) of the data part 120 in track numbers 0-4. Userinformation (subdata 2) is recorded as the subdata (subdata block 2) ofthe data part 120 in track numbers 5-9. The detailed positioning of thesubdata 121 is shown in FIG. 5. Only the subdata 121 of the data part120 recorded to the synchronization block of the subcode area 26 isshown in FIG. 5. The absolute time code (ATC 123) and tape counter (TC124) are recorded to alternating synchronization blocks as the absoluteposition information in tracks 0-4. The recording date (T1 125) andrecording time (T2 126) are similarly recorded to alternatingsynchronization blocks in tracks 5-9. Note that ATC 123, TC 124, T1 125,and T2 126 are recorded together with an ITEM identification header asrequired so that the data content can be is discriminated using theidentification header as may be required during data reproduction.

By thus simultaneously recording a subcode together with the videosignal, tape contents can be more efficiently located and manipulatedduring edit and search operations.

The subcode area 26 of each track is divided into plural (twelve in thisembodiment) synchronization blocks, and a block ID code 114 is includedin the ID data 111 of the ID part 110 of the subcode area 26 in alltracks in this embodiment. By thus recording a block ID code 114 to allsynchronization blocks, the data content of each synchronization blockcan be read during cross-track search operations in which the subcodesynchronization blocks are reproduced and detected, and high speedsubcode searches are possible.

Note that by recording the APID 118 to ID data block 2, this ID can beread during searching operation to determine the subcode data position.This is useful when the meaning of the control ID (COID) is changedaccording to the APID when the user information content and position arechanged according to the APID.

Both the block ID code 114 and APID 118 are recorded to the ID part 110of the synchronization block. The detection rate of data recorded to theID part 110 is greater than that of data recorded to the data part 120during high speed searches. As described above, the reproduction periodrequired to read data recorded to the ID part 110 can be shorter thanthat of data recorded to the data part 120. As a result, the detectionrate during high speed searches increases during cross-track playbackoperations.

By structuring the tracks as described above, ID data 1, ID data 2,subdata 1, and subdata 2 can be edited independently. This means thatduring editing operations in which ID data 1 is re-written, for example,ID data 2, subdata 1, and subdata 2 can be preserved, and the same istrue when editing ID data 2, subdata 1, or subdata 2. The user can beprovided significantly enhanced freedom of use using a function such asthis in a VCR.

Note also that while the indexing ID and program number are recorded asID data 1, search operations for locating a particular scene can be mademuch more effective if the indexing ID can be freely inserted-after theprogram content is recorded. Even in such cases, however, it isnecessary to preserve the other subcode data (APID, COID, absoluteposition information, and/or user information). In other words, beingable to discretely edit the subcode is an extremely meaningful function.

Referring to FIG. 6, a block diagram of a recording and reproducingapparatus according to the present invention is shown, particularlyshowing the parts necessary for re-writing the indexing ID, SRID. Alsoshown in FIG. 6 are an edit position selector switch 29, reproducer 42,tracking error detector 30, positioning information signal detector 31,editing timing generator 32, editing indicator 33, segment numberdetector 34, ID data 1 detector 35, ID data 2 detector 36, subdata 1detector 37, subdata 2 detector 38, add SRID key 40, and erase SRID key41. It is needless to say that the elements 8, 10, 11 and 12 shown inFIG. 1 are equipped in the apparatus shown in FIG. 6.

It is assumed in the following description that the indexing ID (SRID)set signal is recorded for a fixed period of five seconds (150 frames)on tape. In general, the program number will not change during the SRIDset signal recording period, and if the program number of the SRIDre-write period is known, no problems will be caused by simultaneouslyre-writing the SRID and program number.

The editing indicator 33 is formed preferably by a micro-computer, andis programmed to carry out the operation shown in FIGS. 7A and 7B forinserting a new SRID. The SRID write-in operation will be describedbelow in connection with FIGS. 7A, 7B, 10A and 10B. FIG. 10A shows acase when the leading edge of the previously recorded SRID markingexists within a first predetermined advanced distance ΔD1 from aposition where the user intended to insert a new SRID marking, and FIG.10B shows a case when the leading edge of the previously recorded SRIDmarking does not exist in such a predetermined advanced distance ΔD1.

At step S1, it is detected whether or not an add SRID command isproduced by the depression of the add SRID key 40. When the add SRIDcommand is detected, the program goes to step S2 at which the presenttape position is detected and stored as data P2. At step S3, apredetermined tape advanced position P6 is calculated by adding P2 witha first predetermined amount AD1, a first predetermined tape retreatedposition P5 is calculated by subtracting second predetermined amount ΔD2from P2, and a second predetermined tape retreated position P1 iscalculated by subtracting third predetermined amount ΔD3 from P2.According to the preferred embodiment ΔD1>ΔD2 and ΔD2=2ΔD3. Thesepositions are shown in each of FIGS. 10A and 10B.

At step S4, normal replay starts from the position P2 up to the positionP6 (step S7). During this normal replay, it is detected at step S5whether any leading edge of previously added SRID is present or not. Ifsuch a leading edge is detected, the position of the leading edge of theold SRID is stored as data P4, and at the same time, a predeterminedtape retreated position P3 from the leading edge is calculated bysubtracting the third predetermined amount ΔD3 from P4 (step S6).Positions P4 and P3 are shown only in FIG. 10A.

At step S7, the current tape position is detected and is compared withthe position P6. If the current tape position reaches the position P6,the tape stops and is rewound (step S8) until the tape is returned backto position P5 (step S9). When the tape is returned back to position P5,the normal replay starts (S10). During the normal replay and when thetape is advanced to the position P1 (step S11), reset data, such as "0",of SRID is marked on the tape. Such a reset of SRID marking continuesuntil the tape moves to the position P2 (step S13). When the tape isadvanced to the position P2, it is first detected whether the positionsP3 and P4 are recorded or not (step S14). FIG. 10A shows a case whenpositions P3 and P5 are recorded, and FIG. 10R shows a casewhen-positions P3 and P5 are not recorded.

If the positions P3 and P5 are not recorded, the operation advances tostep S19 for start writing a new set data, such as "1", of SRID markingup to the position P6 (step S20).

If the positions P3 and P5 are recorded, the operation goes to step S15to start writing a new set data "1" of SRID marking only up to theposition P3 (step S16). After the position P3, new reset data "0" ofSRID is marked (step S17) up to the position P4 (step S18). Then, fromthe position P4, another new set data "1" of SRID marking starts up tothe position P6 (steps S19 and S20). Thereafter the making stops (stepS21) so that the previously written marking continues thereafter.

As apparent from FIG. 10A, in the case where the leading edge of thepreviously recorded SRID marking "1", exists within the firstpredetermined advanced distance ΔD1 from a position where the userintended to insert a new SRID marking, the old and new SRID markings "1"are separately added by inserting a reset SRID marking "0" betweenpositions P3 and P4.

From FIG. 10B, in the case where the leading edge of the previouslyrecorded SRID marking does not exist in such a predetermined advanceddistance ΔD1, the new SRID marking "1" starts from the intended positionP2 for a predetermined required tape distance ΔD1 with a reset SRIDmarking "0" inserted for a tape distance ΔD3 immediately before theleading edge of the newly added SRID marking "1" so that the newly addedSRID marking "1" it can be distinguished from the old SRID marking "1",if the new marking should start from a middle of the old SRID marking"1".

The operation shown in FIG. 10A is further analyzed in detail below. InFIG. 10A, it is here assumed that an SRID set marking was previouslyrecorded for the fixed period L4 (corresponding to 150 frames) startingfrom position P4; a new indexing ID is to be recorded from a position P2located before P4 in the direction of tape travel, and a new SRID setmarking is to be recorded to enable accessing to position P2. Period(L2+L3+L5=ΔD1) starting from position P2 is equivalent to the 150 frameset signal period, and this period (L2+L3+L5) overlaps the recordingstarting position P4 of the previously recorded SRID set marking. Themethod of writing the new SRID set marking is described below.

The operation is outlined first.

(1) The period (L2+L3+L5=ΔD1) starting from position P2 is firstreplayed to detect the presence of any leading edge of previouslyrecorded SRID set marking within that period.

It is assumed in this example that a leading edge of a previouslyrecorded SRID set marking is detected within the period (L2+L3+L5=ΔD1).

(2) The tape is then rewound. The rewind distance is determined tosatisfy the following conditions.

1. Rewind end position P5 is set at a position on the tape before theposition P1 (the SRID reset signal recording start position, describedin detail below) in the normal tape winding direction with sufficientdistance ΔD3 between rewind end position P5 and position P1 (a) fortracking to be completed during tape travel from P5 to P1, and (b) forat least one frame of data recorded to the subcode area to bereproduced.

2. This distance ΔD3 from P5 to P1 must also be as short as possiblebecause the time required for the edit operation increases the longerrewinding takes.

(3) The tape is then reproduced to detect data from the subcode arearequired to rewrite the SRID.

(4) An SRID reset signal is recorded to period L1, preferably equal toΔD3, starting from position P1.

Period L1 is equivalent to 10 frames, i.e., position P1 is located 10frames before position P2 (a position near to where tape windingstarts).

(5) The SRID set signal is then recorded for the period L2 starting fromposition P2. Period L2 is the period starting from position P2 andending at position P3, and position P3 is at a position period L3 (10frames) before position P4 (the recording start position of thepreviously recorded SRID set signal).

(6) An SRID reset signal is recorded for period L3 starting fromposition P3.

(7) The SRID set signal is recorded for a period L5 starting fromposition P4.

The length of period L5 is equivalent to the fixed period length (150frames) minus the length of periods (L2+L3); The length of periods(L2+L3) is equivalent to the length on tape from position P2 (therecording start position of the new SRID set signal) to position P4 (therecording start position of the previously recorded SRID set signal).

Thus, when the indexing ID is re-written for a fixed period equivalentto 150 frames starting from position P2, it is first determined whethera recording start position for a previously recorded SRID set signal islocated within that fixed period from the starting position of the newset signal. When such a position is detected, as it is assumed to be inthis example, a reset signal is first recorded for a period L1 fromposition P1, the SRID is recorded for a fixed period to P3, a resetsignal is recorded for period L3 from P3, and the SRID set signal isrecorded for period L5.

The operation outlined in steps (1)-(5) above is described in detailbelow.

(1) Detecting an SRID set signal recording start position

The overall operation of the recording and reproducing apparatus isdescribed first (see FIG. 6).

It is assumed that the editing indicator 33 recognizes that a new SRIDset signal is to be recorded from position P2 based on an externalinput. The editing indicator 33 thus instructs the edit positionselector switch 29 to contact pole 29b. The clock generator 9 produces a150-Hz signal, and the rotary head controller 23 controls the velocityof the cylinder 3 on which the rotating heads 2a and 2b are mountedsynchronized to the clock output of the clock generator 9. A reproduce(read) signal is output from rotating head 2a because the edit positionselector switch 29 is switched to pole 29b. Tracking control is alsoapplied based on this output signal. The capstan control circuit 6 isalso instructed to execute tracking control by the editing indicator 33.

The tracking method is described below.

As described above, pilot signals of two different frequencies f1 and f2every other track are recorded frequency multiplexed to the trackingsignal area 28 of the recorded tracks. The tracks are recorded insequence from track 24-0 as f0, f1, f2, f0, f1 . . . The pilot signal isnot recorded to f0 tracks. The pilot signal of frequency f1 is recordedfrequency multiplexed to the f1 tracks. The pilot signal of frequency f2is recorded frequency multiplexed to the f2 tracks.

Tracking is controlled so that rotating head 2a always scans the f0tracks. For example, as shown in FIG. 6, rotating head 2a is controlledto track 24-10. When rotating head 2a scans the tracking signal area 28of track 24-10, the leakage component of the different pilot signalcomponents f1 and f2 recorded to the adjacent tracks 24-9 and 24-11 arealso detected. The tracking error information is detected from thesesignals by the tracking error detector 30, and the capstan controlcircuit 6 controls the capstan motor based on the tracking errorinformation input thereto.

The tracking error detector 30 is a common detector that operates bycomparing the size of the f1 and f2 components and outputting thetracking error information proportionally to the detected difference.The tracking error information always outputs the difference of thepilot component contained in the leading track minus the pilot componentcontained in the trailing track. For example, when the rotating head 2ascans track 24-10, a value proportional to the difference of the pilotcomponent contained in the tracking signal area of track 24-9 subtractedfrom the pilot component contained in the tracking signal area of track24-11 is output. The tracking of rotating head 2b to track 24-11 can besimultaneously maintained by tracking rotating head 2a to track 24-10because rotating head 2b is positioned extremely close to rotating head2a and the relative position of rotating head 2b to rotating head 2a canbe assured.

By thus tracking the rotating heads 2a and 2b to the tape tracks, thesignal reproduced by rotating head 2a is input to the ID data 1 detector35. The tape is driven in a reproducing mode for a 150-frame-equivalentperiod from position P2 to detect whether a set or reset signal isrecorded as the SRID. The SRID set signal recording start position P4 isthus detected, and the tape position is stored by detecting the absoluteposition information recorded as subdata 1. The position P3 is thencalculated from the absolute position information of position P4. Theabsolute position information is thus used as the positioninginformation of the rewrite edit operation. It is thus possible tocalculate position P1 from position P2.

It is also possible to determine the end position of the150-frame-equivalent period from position P2 from the absolute positioninformation (detected by the ID data 1 detector 35), and to execute step(2) when that tape position is reached.

(2) Tape rewind operation

The editing indicator 33 instructs the capstan control circuit 6 torewind the tape. In general, the tape can be rewound at a faster tapespeed than that of the recording and reproducing operations. Trackingcontrol is not required for the rewind operation. It is assumed herethat the rewind tape speed is 3-times the recording speed (i.e., -3×).The information from the subcode area is reproduced from tape whilerewinding, enabling the absolute position information to be detected bythe subdata 1 detector 37 and the tape to be stopped after being rewoundthe preset extra amount from the absolute position of position P1. Asdescribed above, this extra amount from P1 is equivalent to ten frames,and is shown as position P5 in FIG. 10A.

(3) Tape reproducing

Tracking is controlled as described in (1) above while advancing thetape in the reproducing mode. The read signal from rotating head 2a isinput to the ID data 1 detector 35. The ID data 1 generator 13 producesthe same program number as the program number detected by the ID data 1detector 35.

(4) SRID reset recording 1

When the tape is advanced in the reproducing mode to position P1, IDdata 1 is written to the tape as controlled by the editing indicator 33.Note that position P1 is determined from the absolute positioninformation detected by the subdata 1 detector 37 from the reproducedsignal. L1. The SRID reset signal of ID data 1 is recorded in periodDuring the ID data 1 writing operation, the edit position selectorswitch 29 switches at the timing described below between a moderecording the recording signal generated by the recorder 22 and a modereproducing the signals from the rotating heads 2a and 2b. Specifically,the recording signal record mode is selected when the subcode area ofthe tracks to which ID data 1 is recorded are scanned, and the modereproducing the signals from the rotating heads 2a and 2b is selectedwhen all other areas are scanned.

As instructed by the editing indicator 33, the ID data 1 generator 13generates new ID data 1. The program number of this new ID data 1 iswritten to retain the program number by the ID data 1 detector 35 beforethe rewrite operation began. A predetermined block identification codeis also produced as the block identification code. An SRID reset signalis also produced. The resulting ID data 1 is input to the synthesizer20.

Note that when rewriting the ID data 1, a new signal is recorded onlywhen the head scans the subcode area of tracks 0, 1, 2, 7, 8, and 9.When the head scans the subcode area of tracks 3-6, therecorder/reproducer is in the reproducing mode, and data is thereforeread. When rewriting the ID data 1 of the ID part of the synchronizationblocks in the subcode areas recorded to tracks 0, 1, and 2, it isnecessary to simultaneously rewrite the subdata 1 (absolute positioninformation) recorded to the data part of the same synchronizationblocks. It is also essential to retain the previously data in subdata 1.The same subdata 1 is therefore recorded to tracks 3 and 4 in additionto tracks 0, 1, and 2. The subdata 1 recorded to tracks 0, 1, and 2 canthus be produced by a one frame equivalent conversion from the subdata 1obtained by reproducing tracks 3 and 4 in the previous frame.

When rewriting the ID data 1 recorded to tracks 7, 8, and 9, it isnecessary to simultaneously rewrite the subdata 2 (user information )recorded to the data part of the same synchronization blocks. It is alsoessential to retain the previously recorded data in subdata 2. The samesubdata 2 is therefore recorded to tracks 5 and 6 in addition to tracks7, 8, and 9. The subdata 2 recorded to tracks 7, 8, and 9 is the same asthe subdata 2 obtained by reproducing tracks 5 and 6 of the same frame,and can thus be created.

The new subdata 1 is generated by the subdata 1 detector 37 and subdata1 generator 15. The new subdata 2 is generated by the subdata 2 detector38 and the subdata 2 generator 16. Subdata 1 and subdata 2 are theninput to the synthesizer 20.

ID data 2 is not re-written here, and creation of ID data 2 (APID, COID)is therefore not described in detail.

The synthesizer 20 synthesizes the synchronization signal and either IDdata 1 or 2 and either subdata 1 or 2 according to the segment numberdetected by the segment number detector 34.

The segment number detector 34 is able to detect the segment number (thetrack number of the one frame) contained in the video signal of thevideo signal area 25 by demodulating the signal reproduced by therotating heads 2a and 2b. For example, the segment number of track 24-1in FIG. 6 is 0. Because the detected segment number is the segmentnumber from the preceding scan and two channels are simultaneouslyrecorded, the segment numbers of the track currently being scanned andthe track previously scanned by the same head will differ only by two.

Thus, if, as determined from the segment number of the previous scandetected by the segment number detector 34, the segment number of thetrack currently being scanned is 0, 1, or 2, the synthesizer 20synthesizes and outputs the synchronization signal, ID data 1, andsubdata 1. Likewise, if the segment number of the track currently beingscanned is 3 or 4, the synchronization signal, ID data 2, and subdata 1are synthesized and output. If the segment number of the track currentlybeing scanned is 5 or 6, the synchronization signal, ID data 2, andsubdata 2 are synthesized and output. If the segment number of the trackcurrently being scanned is 7, 8, or 9, the synchronization signal, IDdata 1, and subdata 2 are synthesized and output.

The signal output from the synthesizer 20 is then input to the recorder22. The recorder 22 outputs a record signal, whereby the subcode isrecorded to the subcode area, to the edit position selector switch 29according to the clock output of the clock generator 9, the controlstandard for the rotating heads 2a and 2b. This operation creates therecording current.

The operation subsequent to this is described using FIGS. 8 and 9A-9D.FIG. 8 is a block diagram of the editing timing generator 32, and FIGS.9A-9D show a timing chart used to describe the method of determining thesubcode editing timing.

The editing indicator 33 outputs a signal instructing an ID data 1re-write. More specifically, the editing indicator 33 inputs to theediting timing generator 32 a signal instructing that the subcode areabe re-written when the segment number is 0, 1, 2, 7, 8, or 9. Thisinstruction signal is output for a period equivalent to (150+10) frames(the period L1+L2+L3+L5) in FIG. 10A, i.e., during the operationdescribed in steps (4) through (7).

While the edit position selector switch 29 is switched to pole 29b, thesignal from the rotating head 2a is separately input to the positioninginformation signal detector 31. The positioning information signaldetector 31 detects the positioning information signal recorded to thepositioning signal area 27 in one part of the tracking signal area ofthe scanned track, and generates the pulse signal expressing theposition of the positioning signal as shown in FIG. 9B. This pulsesignal is input to the editing timing generator 32.

The segment number detector 34 detects the segment number (the tracknumber of the frame) contained in the video signal of the video signalarea 25 by demodulating the reproduced signal. The detected segmentnumber is input to the editing timing generator 32.

When rewriting the subcode area of a specific track in one frame, it isnecessary to specify the track (segment) number being rewritten, and thestarting and end positions in that track. The editing timing generator32 generates the timing signal at which the edit position selectorswitch 29 switches between poles 29a and 29b based on the output signalfrom the editing indicator 33, the pulse signal output by thepositioning information signal detector 31, and the segment numberoutput from the segment number detector 34.

The operation of the editing timing generator 32 is described in detailnext.

The output signals from the editing indicator 33 and the segment numberdetector 34 are input to the comparative operator 32a of the editingtiming generator 32. Based on the output from the segment numberdetector 34, the comparative operator 32a detects the track number ofthe next track to be scanned. The comparative operator 32a sets theoutput signal INS₋₋ TR to HIGH if this track number matches the tracknumber input from the editing indicator 33, and otherwise sets theoutput signal INS₋₋ TR to LOW. Because the segment number detector 34detects the segment number contained in the video signal recorded to thevideo signal area 25 at this time, the segment number stored while therotating head 2a scans the subcode area 26 or the tracking signal area28 is the segment number of the previous scan.

The pulse signal output from the positioning information signal detector31 is input to the first and second delay circuits 32b and 32c. Eachdelay circuit then begins counting the internal fixed clock of therecording and reproducing apparatus shown in FIG. 9A, and creates adelay signal by counting this internal clock for a period equivalent tothe specified delay times t1 and t2. The subcode editing timing signalshown in FIG. 9C is then generated by inputting these delay signals tothe R-S flip-flop 32d as shown in FIG. 8. The subcode editing timingsignal is input with the INS₁₃ TR output signal of the comparativeoperator 32a to AND circuit 32e, and the output of this AND operation isinput to the edit position selector switch 29 as the ID data 1 editingtiming signal.

The edit position selector switch 29 switches from pole 29b to pole 29aonly when the ID data 1 editing timing signal thus generated is HIGH,causing a new record signal to be applied to the rotating head 2a and anew ID data 1 to be overwritten to the subcode area of the tracks towhich ID data 1 is recorded. Note that this operation continues untilposition P2 is reached.

(5) SRID set recording 1

When position P2 is reached in step (4) above, a set signal is recordedas the SRID of ID data 1 according to the instructions from the editingindicator 33. Note, again, that position P2 is determined from theabsolute position information detected by the subdata 1 detector 37 fromthe signal reproduced from tracks 3 and 4. This operation differs fromthat in (4) above in that a set signal is generated in place of a resetsignal as the SRID by the ID data 1 generator 13. The rest of theoperation is the same as that described above, and redundant descriptionis therefore omitted.

(6) SRID reset recording 2

When position P3 is reached in step (5) above, a reset signal isrecorded as the SRID of ID data 1 as instructed by the editing indicator33. Note that position P3 is determined from the absolute positioninformation detected by the subdata 1 detector 37 from the signalreproduced from tracks 3 and 4. This operation is, in principle, thesame as that in (4) above, and continues until position P4 is reached.

(7) SRID set recording 2

When position P4 is reached in step (6) above, a set signal is recordedas the SRID of ID data 1 according to the instructions from the editingindicator 33. Note that position P4 is determined from the absoluteposition information detected by the subdata 1 detector 37 from thesignal reproduced from tracks 3 and 4. This operation is the same asthat in (5) above, and continues through period L5. Tape travel is thenstopped and the re-write edit operation is completed.

By creating the recording current and determining the re-write timing bythe above method, insertion edit operations whereby, for example, IDdata 1 is re-written while preserving the content and integrity of IDdata 1 and subdata 1 and 2 are made possible. This operation results inthe indexing ID (SRID) as shown at the bottom of FIG. 10A.

If the SRID is rewritten as described above, it will always be possibleto detect or discriminate the recording start position of a previouslyrecorded SRID set signal and the recording start position of the newlyrecorded SRID set signal. More specifically, it is possible determinethe recording start position of a newly recorded SRID set signal when anSRID establishing a new indexing position is recorded in the middle of apreviously recorded indexing period. When the newly recorded SRID setsignal period overlaps the starting position of a previously recordedSRID set signal recording period, it also remains possible to determinethe starting position of the previously recorded set signal period. Inother words, all indexing information is retained even after recording anew indexing ID set signal because the SRID signal always changes fromthe SRID set signal level to a reset signal level between SRID periods.

The case shown in FIG. 10B is described next. As shown in FIG. 10B, itis assumed that an SRID set signal has been previously recorded forperiod L11 (equivalent to 150 frames) starting at position P11, and anew SRID set signal is to be recorded to enable indexing to position P2in period L11. Note that the new SRID set signal is to be recorded forthe standard fixed length period of 150 frames (period L13 in FIG. 10B),and that there are no recording start positions for other previouslyrecorded SRID set signal periods within period L13. The SRID rewriteoperation for this case is described below.

(11) The period L13 starting from position P2 is reproduced to detectthe presence of any SRID set signal recording start positions withinthat period. It is assumed in the following description that there areno SRID set signal recording start positions within period L13. The casein which an SRID set signal recording start position is detected withinthe new SRID recording period is described above with reference to FIG.10A.

(12) The tape is then rewound after reproducing period L13. The rewinddistance is determined to satisfy the following conditions.

1. Rewind end position P5 is set at a position on the tape before theposition P1 (the new SRID recording start position, described in detailbelow) in the normal tape winding direction with sufficient distancebetween rewind end position P5 and position P1 (a) for tracking to becompleted during tape travel from P5 to P1, and (b) for at least oneframe of data recorded to the subcode area to be reproduced.

2. This distance from P5 to P1 must also be as short as possible becausethe time required for the edit operation increases the longer rewindingtakes.

(13) The period from position P5 to position P1 is then reproduced todetect the data of the subcode area required to rewrite the SRID.

(14) An SRID reset signal is recorded to period L12 starting fromposition P1.

Period L12 is equivalent to 10 frames, i.e., position P1 is located 10frames before position P2.

(15) The SRID set signal is then recorded for the fixed period L13starting from position P2. Note that period L13 is equivalent to 150frames.

An indexing ID (SRID) as shown in FIG. 10B is recorded to tape as aresult of this operation. Note that, as described with FIG. 10A above,ID data 1 and subdata 1 and 2 are preserved because the same operatingprinciple is applied.

If the SRID is rewritten as described above, it will always be possibleto detect or discriminate the recording start position of a previouslyrecorded SRID set signal and the recording start position of the newlyrecorded SRID set signal. Specifically, the SPID signal level alwayschanges from the reset signal level to the set signal level of theindexing ID period at the SRID recording start position, and it istherefore possible to find the SRID recording start positions bysearching for these positions where the signal level changes.

FIG. 11 shows another example of the content and positioning of the IDdata 111 and subdata 121 of the subcode. In this case the ID data is thesame in all tracks of a single frame. Subdata recording is the same asdescribed above with reference to FIG. 4, and further description istherefore omitted.

The ID data 111 of this embodiment in described next in the headscanning sequence. A 4-bit synchronization block number 113 is firstrecorded; this is the same as in FIG. 4. A 2-bit block ID code 114 isthen recorded. In this case there is only one ID data block but twosubdata blocks, and there are therefore two possible combinations of IDdata blocks and subdata blocks. This means that it is sufficient if theblock ID code 114 can distinguish between blocks to which subdata 1 isrecorded (subdata block 1) and blocks to which subdata 2 is recorded(subdata block 2). Therefore, b"00" is recorded as the blockidentification code to tracks 0-4 to which subdata 1 is recorded, andb"10" is recorded as the block identification code to tracks 5-9 towhich subdata 2 is recorded. A 1-bit SRID 115 and 1-bit PHID 131 arethen recorded. The SRID 115 is the indexing ID as described above. ThePHID 131 is an ID code for searching for periods to which a desiredimage is recorded.

The SRID set signal is recorded to the recording start position of arecorded program, and the PHID 131 is recorded as a set bit during theperiod of the program to which an image (motion or still) that is to besearchable is recorded. A 4-bit APID 118 and a 4-bit program number(PN0) 132 are then recorded. It is further assumed in this embodimentthat the SRID and PHID will not be simultaneously set. It is possible inthis case to record the program number as the PN0 132 in those periodsin which the SRID is set, and to record a number corresponding to therecorded image data as the PN0 132 in those periods in which the PHID isrecorded set. This configuration can provide a superior search functioncapability in VCR devices. In other words, this configuration makes itpossible to search for the SRID while confirming the program number, orto search for a PHID while confirming the image data number. That thesubcode area can be used more efficiently with this configuration thanwhen the image data number and program number are recorded to separateareas will be obvious.

Next, the operation for rewriting the SRID or PHID in ID data recordedas shown in FIG. 11 is described next. The PHID rewrite operation isdescribed below. When the PHID (or SRID) is rewritten in thisembodiment, the subcode area of all tracks in the corresponding periodis rewritten. It is necessary, however, to retain the data contentwritten to all parts other than the PHID bit. The overall timing of theoperation is as described in the previous embodiment. In other words,when recording a new PHID set bit to a previously recorded tape, theoperation described in steps (1)-(7) and in steps (11)-(15) is the sameas that with the data structure shown in FIG. 4. These operationsdiffer, however, in the method of generating the SRID, APID, and PN0contained in the ID data, and the new subdata 1 and subdata 2, in(4)-(7) and (14), (15).

As described above in the previous embodiment using the data structurein. FIG. 4, the mode driving the tape in a data read state ((3) or (13))changes to a mode rewriting the subcode area ((4)-(7) or (14), (15)) ata specific timing during the rewrite editing operation. The new subdata1 in this embodiment is generated by incrementing the subdata 1(absolute position information) detected by the subdata 1 detector 37during tape travel in the reproducing mode from the moment the rewritemode is selected (the moment subdata input from the subdata 1 detector37 stops). Subdata 2 (user data) is similarly created by the subdata 2detector 38 and subdata 2 generator 16.

The SRID is the same SRID data detected by the ID data 1 detector 35during tape travel in the reproducing mode. If an SRID is set in thisperiod, it will be recorded for a period longer than the predeterminedspecified period, but this poses no practical problems.

Likewise, the APID is the same APID data detected by the ID data 1detector 35 during tape travel in the reproducing mode. Because of thenature of toe APID data, creating the APID data in this way completelypreserves the previously recorded information.

A number corresponding to the newly recorded PHID is recorded for thePN0. In this embodiment, the desired number is generated by the ID data1 generator 13.

A number corresponding to the subdata (subdata 1 or 2) recorded to thattrack is generated as the block identification code.

All data other than the PHID data is thus created in the PHID rewriteperiod (both the PHID set and reset signal level periods).

The operation is, in principle, the same when rewriting the SRID. Thenew PHID in this case is the same as the PHID data detected by thesubdata 1 detector 37 during tape data reproduction.

The information other than the PHID or SRID information rewritten in theabove operations can store the same data previously recorded to the sametape (rewrite) period if it is generated as described above. The PHID orSRID is recorded in the case of the previous embodiment as describedusing FIG. 10A or 10B. Therefore, when a new PHID or SRID is recorded atthe set signal level to a previously recorded tape, it is alwayspossible to detect the recording start positions of the new andpreviously recorded data as described in the previous embodiment.

If an editable indexing ID is recorded as described above, it ispossible to link other operations with the indexing ID. For example, itis possible to record a print command data associated with a PHID, andthereby print while reproducing a desired image. To enable this, whenthe ID data is recorded as shown in FIG. 11, the APID 118 is recordedwith three bits instead of four, and the 1-bit thus saved is recorded asa PRM. That part of an image period recorded with a set PHID bit whichis to be printed is therefore recorded with the PRM also set. By thenconnecting the recording and reproducing apparatus to a printer, theimage recorded with a set PRM bit can be output to the printer when theset PRM bit period is detected by the ID data 1 detector during datareproducing.

A recording and reproducing apparatus with excellent ease of use canthus be provided by recording a PRM bit and linking operation to thePHID during tape reproduction modes. For example, it is possible toperform a high speed search for images recorded with the PHID set, andoutput the image to a printer if the PRM is also recorded set. Functionssuch as this are extremely useful with digital VCRs featuring aninherently high image quality.

Note that functions using this PRM bit shall not be limited to the aboveprinter example, and the PRM bit can be used to, for example, transmitthe image data to another storage media. In addition, the PRM recordingposition shall not be limited to the PHID set recording is period. ThePRM may be recorded to the reset signal level recording periodimmediately preceding or immediately following the PRID set recordingperiod. In either case, such functions can be achieved insofar as therelationship to the PHID set recording period is fixed, and theassociation with the PHID can be maintained after PHID rewriting.

Next, the edit operation for indexing ID erasure (reset signal levelrewriting) is described using the data structure shown in FIG. 4.

The editing indicator 33 is also programmed to carry out the operationshown in FIGS. 12A and 12B for erasing the old SRID. The SRID erasingoperation will be described below in connection with FIGS. 12A, 12B, 13Aand 13B.

FIG. 13A shows a case when there is another previously recorded SRIDmarking immediately before the SRID marking which the user intends toerased, and FIG. 13B shows a case when there is no previously recordedSRID marking immediately before the SRID marking which the user intendsto erased.

Referring to FIGS. 12A and 12B, before the start of the flow chart, itis to be noted that the tape is stopped at a position within thepreviously recorded SRID marking which the user intends to erase.

At step S31, it is detected whether or not an erase SRID command isproduced by the depression of the erase SRID key 41. When the erase SRIDcommand is detected, the program goes to step S32 at which the presenttape position is detected and stored as data P20. At step S33, apredetermined tape advanced position P37 is calculated by adding P20with a first predetermined amount ΔD7. At step S34, the tape is rewounduntil the leading edge of the set SRID is detected (step S35), and thedetected position is stored as position P24 (step S36). A predeterminedtape position P22 before the position P24 is calculated by subtracting apredetermined amount ΔD6 from position P24 (step S37). It is noted thatΔD6>ΔD3. Then, the tape is further retreated to position P22 (step S38).

Then, at step S39, it is detected whether the SRID at position P22 isreset, or not. If it is not reset, as in the case shown in FIG. 13A, theoperation goes to step S40, but if it is reset, as in the case shown inFIG. 13B, the operation goes to step S44.

At step S40, a predetermined retreated position P23 from position P24 iscalculated by subtracting the predetermined amount ΔD3 from positionP24. Then, the tape is replayed from position P22 up to position P23(steps S41 and S42). Then, at step S43, a new set data "1" of SRIDmarking is written up to the position P24.

By this operation, as understood from FIG. 13A, the two subsequent setSRID markings are joined to present one set SRID marking. In otherwords, the latter of the two subsequent set SRID markings is erased, andis absorbed in the former set SRID marking.

At step S44, the tape is replayed and advanced to position P20.Thereafter, the tape is further advanced and the trailing edge of theset SRID marking is detected (step S46). When the trailing edge of theSRID marking is detected, the trailing edge position is stored asposition P34 (step S47). Thereafter, a fast rewind is effected to returnthe tape back to the position P22 (step S48). Then, the tape is replayedup to position P24 (step S49). Then, at step S50, a new reset data "0"of SRID marking is written up to the position P34 to eventually erasethe former of the two subsequent set SRID markings.

The operation shown in FIG. 13A is further analyzed in detail below. InFIG. 13A, it is here assumed that the SRID as shown in FIG. 13A waspreviously recorded to tape. Also in FIG. 13A, period L21 is the SRIDset period for indexing position P21 and is 60 frames long; period L22(=ΔD3) is a 10 frame reset period; and period L23 is a 150-frame SRIDset period for indexing position P24.

The SRID is normally recorded to a fixed length period from the positionto be indexed. It is assumed here that an SRID set marking for indexingposition P21 was previously recorded to a 150-frame fixed period (5 sec.equivalent) from position P21. After that, however, a reset marking wasrecorded to period L22 and the SRID set marking was recorded to thefixed period L23 to enable indexing a new position at position P24,resulting in the signal shown in FIG. 13A (a). It is to be noted thatthe length of the reset period L22 simply needs to be short relative tothe length of the set signal period L23, and it is assumed in thefollowing description to be equivalent to ten frames.

As a result of the SRID rewrite operation resulting in the above signal(FIG. 13A), the heads can be indexed to both position P21 and P24. Note,also, that the above operation is as described previously using FIG.10B. The object of the operation described below is to erase theinformation for indexing to position P24.

The method conventionally used is described first. Because it isbasically sufficient to erase the information for indexing to positionP24, the conventional method simply rewrites period L23 to the resetsignal level. Doing so, however, results in the ID information forindexing to position P21 being only 60 frames long, significantlyreducing the reliability of high speed search operations looking forposition P21. The detection rate of the ID information during high speedsearches is highly dependent upon the recording time of the ID setsignal. To resolve this problem of the prior art, the method of thepresent invention is proposed as described below.

Only the outline of this operation is described below because thedetails of the operation are the same as described above with referenceto FIG. 10A.

(21) Tape rewinding and SRID set signal recording period detection

The edit operation is assumed to begin from position P20. The first stepis to rewind the tape while detecting the SRID from the signalreproduced during rewinding. Note that while in this example the SRID isdetected to a position 15 frames before position P24, the length of thisdetection period is determined according to the length of the resetsignal period L22 recorded during the SRID set signal rewrite operation.It is furthermore preferable to detect the SRID signal for a periodslightly longer than the length of the reset signal period L22 (thereset signal period L22 is 10 frames in this example).

When it is detected that the SRID signal has changed from the reset tothe set signal level, the tape is driven an additional 15 frames in thesame direction and then stepped at position P22.

The case in which the SRID is not detected to change from the resetlevel to the set signal level within the 15 frame period precedingposition P24 is described later.

(22) Tape reproduction

The tape is then read to detect the subcode area data required whenrewriting the SRID.

(23) SRID reset recording

The SRID is recorded at the set level in period L22 from position P23 toposition P24.

The SRID signal shown in FIG. 13A is obtained from the above operation.In other words, the information needed for indexing to position P24 hasbeen erased.

By erasing the information for indexing to position P24 in this way, theSRID signal for indexing to position P21 is set for the period fromposition P21 to position P26, i.e., a period sufficiently long for goodhigh speed search performance. The ability to conduct high speedsearches for position P21 is thus maintained.

While the SRID period for indexing position P21 is longer than 150frames (210 frames in this example) after the rewrite (erase) operation,this does not adversely affect the high speed search performance, itactually increases search efficiency, and therefore creates no problem.It is necessary to assume in subsequent rewrite operations that the SRIDset signal is recorded to a period longer than the specified 150 frameperiod.

In addition, while in the above example the period L22 is rewritten tothe set signal level, it is also possible to write the SRID set signallevel for a 150-frame period from position P21, and to write a resetsignal level following that 150-frame period. This case is also withinthe scope of the invention.

Note, further, that the above case applies when there is an SRID setsignal period that must be preserved within a predetermined periodbefore (15 frames in the above example) the recording position of theSRID to be erased. An alternative case wherein an SRID set signal periodthat must be preserved does not exist within the predetermined periodbefore the recording position of the SRID to be erased is describedbelow. More specifically, a reset-set signal level change in the SRID isnot detected while rewinding the tape 15 frames from position P24. Inthis situation it is sufficient to record a reset signal level to theset signal period of the SRID to be erased.

Another example of the edit operation when erasing the indexing ID(reset signal rewrite) is described next with reference to FIG. 13B. Inthis example the indexing ID (SRID) set signal has been recorded to tapefor five seconds (150 frames). The SRID has also been edited, resultingin the SRID signal shown in FIG. 13B (a): the set signal period fromposition P24 to P34 is 100 frames, the reset signal period from positionP34 to P35 is 10 frames, and the set signal period from position P35 toP36 is 150 frames. The object of the following operation is to erase theSRID set signal from position P24 to position P34 on tape.

The conventional method is described first. Because it is basicallysufficient to erase the information for indexing position P24, andbecause an SRID is recorded set for 150 frames, a reset signal level issimply recorded for 150 frames from position P24. In this case, the SRIDset signal for indexing position P35 is erased (rewritten to the resetsignal level).

As described above, the SRID after editing is not necessarily recordedto a continuous 150 frame period. To resolve this problem of the priorart, the method of the present invention is proposed as described below.

Only the outline of this operation is described below.

(31) The SRID erase (rewriting to the reset signal level) operation isstarted from position P20. The tape is first driven in a read mode todetect the SRID. The position of the SRID set-reset signal level changeis detected and stored as position P34. Step (32) is then executed.

(32) The tape is then rewound to rewind end position P22, which isapproximately ΔD6 before the start position P24 of the SRID set periodto be erased. This position is determined to assure sufficient tapetravel for tracking to be completed from position P22 to position P24.Tracking must be completed.

(33) The tape is then reproduced to detect the subcode area datarequired when rewriting the SRID.

(34) The SRID is recorded at the reset level from position P24 toposition P34.

During the SRID reset level rewrite operation above, any positions atwhich the SRID signal changes from the set to the reset signal level arefirst detected, and the reset level is then recorded to a position (P34)before the reset recording period. If the SRID is reset in this way, itis possible to reset only the SRID set period to be erased, and theproblem of also erasing other SRID set periods that are not to be erased(the period from position P35 to P36 in FIG. 13B) is eliminated. Thismethod is extremely useful because the SRID set signal recording startposition is extremely important for search and edit operations.

The above erasing method is also useful when the SRID set recordingperiod to be erased is longer than the specified recording period. Morespecifically, incomplete erasing does not occur because the entireperiod to the end position of the SRID set recording period to be erasedcan be reliably rewritten to the reset signal level.

In the case of the above embodiment, the period from position P24 to P34is reset, but it is also possible to write the reset signal level fromposition P24 to P35. In this case, however, after detecting position P34in step (31), it is necessary to advance the tape in the reproductionmode for a predetermined number of frames to detect and store theposition of position P35. It is preferable for this predetermined numberof frames to be slightly more than the reset signal recording periodrecorded before the SRID set signal period (15 frames in thisembodiment). If an SRID set signal recording start position cannot bedetected within this predetermined number of frames from position P34,it is sufficient to simply record the reset level to position P34.

It is also possible to switch between the operations shown in FIGS. 13Aand 13B as the situation requires. Step (21) may also be executed afterstep (31), i.e., it is possible to combine the operations shown in FIGS.13A and 13B within the scope of the invention.

It is to be noted that the above embodiments have been described withrespect to a two channel recording and reproducing apparatus, but thepresent invention shall not be limited to the combination or placementof rotating heads described above, and can be applied to various othercombinations.

These embodiments are also described with a subcode area providedbetween the tracking signal area and video signal area, but the specificposition of the subcode area on tape shall not be so limited. Forexample, the subcode area may be provided in the second half of thetrack after the video signal area seen in the head scanning directionwithin the scope of the invention.

The present embodiments are also described using a 30 frames/secondvideo-signal, but the number of frames shall not be so limited. Oneframe of the video signal is also described as being recorded in tensegments to ten tracks, but the invention shall not be limited to thisnumber of segments.

The present embodiments are also described with reference to a videosignal recording and reproducing apparatus, but the invention isobviously applicable to an audio signal recording and reproducingapparatus.

The present embodiments are also described with reference to two typesof pilot signals for tracking, but pilot signals of four frequencies canalso be used as in the 8-mm VCR format, the recording position of thepilot signal can be changed as in the DAT format with only one pilotsignal used, and the pilot signal input method is also not limited tothat described above.

Furthermore, tracking control in the invention is accomplished using apilot signal frequency multiplexed to the tracking signal area at thebeginning of the track, but it is also possible to record only thepositioning information signal for editing operations to the trackingsignal area and to use a control signal recorded to a linear track atthe tape edge as in the conventional VHS video format for trackingcontrol.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

What is claimed is:
 1. A recording and reproducing apparatus forrecording video signal and indexing signal to seperate video signalareas and subcode areas, respectively, of diagonal tracks formed on atape by a rotating head, said apparatus comprising:tape drive means fordriving the tape; an add command generator for generating an add commandto add said indexing signal; an indexing signal control for setting andresetting said indexing signal; recording means for recording the videosignal to the video signal area and the indexing signal, if any, to thesubcode area of each track; reproducing means for reproducing a recordedsignal from said tape; switching means for switching between a recordingmode in which said recording means is connected to said head and areproducing mode in which said reproducing means is connected to saidhead; indexing signal detection means for detecting set and reset statesof said indexing signal during said reproducing mode; and editingcontrol means for controlling said indexing signal control in responseto said add command such that a portion of the tape is reproduced for asecond predetermined amount to detect any leading edge of previouslyrecorded indexing signal, and if a leading edge of a previously recordedas a set state from a first said indexing signal is recorded as a setstate from a first position where said add command is generated to asecond position which is before said leading edge by a firstpredetermined amount, wherein, if said leading edge is detected, saidediting control means preserves said leading edge on said tape whenrecording said indexing signal.
 2. A recording and reproducing apparatusas claimed in claim 1, wherein said editing control means furthercontrols said indexing signal generator such that a reset state isrecorded before said first position for said first predetermined amount.3. A recording and reproducing apparatus for recording video signal andindexing signal to separate video signal areas and subcode areas,respectively, of diagonal tracks formed on a tape by a rotating heads,said apparatus comprising:tape drive means for driving the tape; anerase command generator for generating an erase command to erase apreviously stored indexing signal; an indexing signal control forsetting and resetting said indexing signal; recording means forrecording the video signal to the video signal area and the indexingsignal, if any, to the subcode area of each track; reproducing means forreproducing a recorded signal from said tape; switching means forswitching between a recording mode in which said recording means isconnected to said head and a reproducing mode in which said reproducingmeans is connected to said head; an indexing signal detection means fordetecting the leading and trailing edges of the indexing signal duringsaid reproducing mode; and editing control means for controlling saidindexing signal control in response to said erase command such that thetape is rewound to a third position past a third predetermined amountfrom a fourth position corresponding to the leading edge of saidpreviously stored indexing signal, then the tape is reproduced to afifth position corresponding to said trailing edge of said previouslystored indexing signal, then recording the indexing signal as a resetstate from said fourth position to said fifth position to erase saidpreviously stored indexing signal.
 4. A recording and reproducingapparatus for recording video signal and indexing signal to seperatevideo signal areas and subcode areas, respectively, of diagonal tracksformed on a tape by a rotating head, said apparatus comprising:tapedrive means for driving the tape; an erase command generator forgenerating an erase command to erase a previously stored indexingsignal; an indexing signal control for setting and resetting saidindexing signal; recording means for recording the video signal to thevideo signal area and the indexing signal, if any, to the subcode areaof each track; reproducing means for reproducing a recorded signal fromsaid tape; switching means for switching between a recording mode inwhich said recording means is connected to said head and a reproducingmode in which said reproducing means is connected to said head; anindexing signal detection means for detecting the leading and trailingedges of the indexing signal during said reproducing mode; and editingcontrol means for controlling said indexing signal control in responseto said erase command such that when the previously stored indexingsignal to be erased is preceded by another previously stored indexingsignal with an interspace between said two previously stored indexingsignals being less than a fourth predetermined amount, said interspaceis recorded with set state of said indexing signal to merge saidpreviously stored indexing signal to said another previously storedindexing signal.
 5. A recording and reproducing apparatus as claimed inclaim 4, wherein said editing control means controls said indexingsignal control in response to said erase command such that the tape isrewound to a fifth position past a third predetermined amount from afourth position corresponding to a leading edge of said previouslystored indexing signal, then when set state of said indexing signal isdetected at said fifth position, indexing signal is recorded as a setstate from a sixth position, which is before said fourth position by afourth predetermined amount, to said fourth position.